System and method for aircraft infrared countermeasures to missiles

ABSTRACT

Apparatus and method for directing a laser beam at an object. Some embodiments include generating direction-control information, based on the direction-control information, directing laser energy into a first fiber at a first end of a first fiber bundle during a first time period, forming an output beam of the laser energy from the second end of the first fiber bundle, and steering the output beam of the laser energy from the first fiber in a first selected direction of a plurality of directions during the first time period, and optionally modulating an intensity of the laser energy according to a predetermined pattern. The direction-control information is based on sensing electromagnetic radiation from a scene. Some embodiments use a remote camera wire-connected to the image processor to obtain scene information, while other embodiments use a second fiber bundle to convey image information from an external remote lens to a local camera.

RELATED APPLICATIONS

This invention claims benefit of U.S. Provisional Patent Application60/740,968 filed on Nov. 29, 2005, which is hereby incorporated byreference in its entirety.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with Government support under contract numberDAAB0701-D-G001 from the U.S. Army. The government has certain rights inthis invention

FIELD OF THE INVENTION

The present invention relates to laser-beam pointer devices, and moreparticularly to apparatus and method for infrared countermeasures (IRCM)to missiles launched against vehicles such as airborne helicopters, Navyvessels, and Army tanks by quickly determining a direction (e.g., towardan incoming missile) to which to point a modulated IR laser beam and fordirecting the laser beam in the determined direction.

BACKGROUND OF THE INVENTION

Advanced Man-Portable Air Defense Systems (MANPADS) present asignificant threat to fixed-wing aircraft and helicopters. Mid-infraredlaser-based infrared countermeasures (IRCM) systems could provide theneeded protection from MANPADS for many types of aircraft.Unfortunately, with the complex pointer/tracker-turret assembly, thesesystems typically cost more than $1.5 million. This prohibitively highcost precludes use with large numbers of aircraft, leaving themunprotected from advanced MANPADS.

Laser beams can be pointed using a number of methods and mechanisms,some which allow aligning the laser beam with a sensor-determineddirection, which is useful for IRCM. Among these are methods usingturrets and/or one or more gimbaled mirrors, for example U.S. Pat. No.6,020,955 “System for pseudo on-gimbal, automatic line-of-sightalignment and stabilization of off-gimbal electro-optical passive andactive sensors” issued Feb. 1, 2000 to Peter Messina, and which isincorporated herein by reference. Messina describes an optical apparatusfor use in auto-aligning line-of-sight optical paths of at least onesensor and a laser, comprising: at least one reference source foroutputting at least one reference beam that is optically aligned withthe line-of-sight of the at least one sensor, a laser reference sourcefor outputting a laser reference beam that is optically aligned with theline-of-sight of the laser, a laser alignment mirror for adjusting thealignment of the line of sight of the laser beam, a sensor alignmentmirror for adjusting the alignment of the at least one sensor, combiningoptics for coupling the plurality of reference beams along a commonoptical path, gimbal apparatus, a detector disposed on the gimbalapparatus for detecting the plurality of reference beams, a finestabilization mirror disposed on the gimbal apparatus for adjusting theline of sight of the optical paths of the at least one sensor and thelaser, and a processor coupled to the detector, the laser alignmentmirror, the sensor alignment mirror, and the fine stabilization mirrorfor processing signals detected by the detector and outputting controlsignals to the respective mirrors to align the line-of-sight opticalpaths of the sensor and the laser. Other such systems or components aredescribed in U.S. Pat. No. 6,288,381 issued Sep. 11, 2001 to PeterMessina titled “Integrated system for line-of-sight stabilization andauto-alignment of off-gimbal passive and active electro-opticalsensors”, U.S. Pat. No. 6,878,923 issued Apr. 12, 2005 to CarlosCasteleiro titled “Low profile optical imaging system having a widefield of regard”, and U.S. Pat. No. 6,879,447 issued Apr. 12, 2005 toCarlos Casteleiro titled “Optical gimbal apparatus” which are allincorporated herein by reference. Such systems are complex andexpensive.

U.S. Pat. No. 6,873,893 issued Mar. 29, 2005 to Sanghera et al. titled“Missile warning and protection system for aircraft platforms”, and U.S.Pat. No. 6,813,296 issued Nov. 2, 2004 to Goyal et al. titled “GASB-cladmid-infrared semiconductor laser”, which are incorporated herein byreference, describe other components that are used in some embodimentsof the present invention.

There is a need for a low-cost laser pointer system that is much lesscomplex than a conventional pointer/tracker-turret assembly.

BRIEF SUMMARY OF THE INVENTION

Novel technology of some embodiments of the present invention has beendemonstrated in proof-of-concept breadboard experiments that, in someembodiments, offer protection from MANPADS via fiber-bundle-basedlow-cost laser pointing functions for 1/10th the cost of conventionalturret or gimbal-based laser-pointer IRCM systems (such as thosedescribed in the above-cited patents), e.g., for any mobile platform(such as various aircraft such as low-thermal-signature rotary-wing Armyplatforms, nautical ships such as Navy destroyers, or land vehicles suchas Army tanks or Humvees) or any fixed platform (such as a land-basedcommunications center).

In some embodiments, the present invention provides a low-cost IRCMsystem that uses a distributed-aperture (i.e., a system with a pluralityof remote lenses, each lens directing one or more beams from a pluralityof optical fibers) beam-steering system, eliminating the mechanical two-or three-axis gimbaled pointer. The pointer/tracker assembly is also theleast reliable component in conventional laser-pointer or other IRCMsystems. Further, the low-cost method and apparatus of the presentinvention use the existing or Common Missile Warning Sensor (CMWS) orother conventional sensors for tracking what the laser beam should pointat (e.g., incoming missiles), eliminating the costly fine-track infraredcamera.

In some embodiments, the present invention provides an apparatus thatincludes a first fiber bundle having a plurality of light-transmittingfibers including a first fiber, a second fiber, and a third fiber, thefirst fiber bundle having a first end and a second end, a laser thatemits laser energy, a processor that generates direction-controlinformation, a fiber selector that is operatively coupled to theprocessor and based on the direction-control information, is configuredto direct the laser energy into the first fiber at the first end of thefirst fiber bundle during a first time period, and transform opticslocated to receive the laser energy from the second end of the firstfiber bundle and configured to form an output beam of the laser energyfrom the first fiber in a first selected direction of a plurality ofdirections during the first time period. Some embodiments furtherinclude a modulator that modulates an intensity of the laser energyaccording to a predetermined pattern. Some embodiments further include asensor operatively coupled to receive electromagnetic radiation from ascene and to transmit sense information to the processor based on thereceived electromagnetic radiation, and wherein the processor isconfigured to generate the direction-control information based on thesense information. Some embodiments further include an ability to sensemore than one object and simultaneously direct a plurality of laserbeams in a plurality of different directions or sequentially direct asingle laser beam in the plurality of different directions one at atime.

Another aspect of the invention, in some embodiments, is a method thatincludes providing a first fiber bundle having a plurality oflight-transmitting fibers including a first fiber, a second fiber, and athird fiber, the first fiber bundle having a first end and a second end,generating direction-control information, based on the direction-controlinformation, directing laser energy into the first fiber at the firstend of the first fiber bundle during a first time period, forming anoutput beam of the laser energy from the second end of the first fiberbundle, and steering the output beam of the laser energy from the firstfiber in a first selected direction of a plurality of directions duringthe first time period.

In other embodiments, the present invention provides an apparatus thatincludes a first fiber bundle having a plurality of light-transmittingfibers including a first fiber, a second fiber, and a third fiber, thefirst fiber bundle having a first end and a second end, means forgenerating direction-control information, means for directing laserenergy, based on the direction-control information, into the first fiberat the first end of the first fiber bundle during a first time period,means for forming an output beam of the laser energy from the second endof the first fiber bundle, and means for steering the output beam of thelaser energy from the first fiber in a first selected direction of aplurality of directions during the first time period.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a sensor/laser-pointer (e.g., IRCM) system 100that illustrates a one-to-one correspondence between the receiveraperture and transmitting fiber according to some embodiments of theinvention.

FIG. 2 is a system block diagram for a low-cost sensor/laser-pointersystem 200.

FIG. 3 is a block diagram of signal losses for one embodiment of alaser-pointer system 300.

FIG. 4 shows one overall system concept for a low-costdistributed-aperture beam-steering laser-pointer system 400.

FIG. 5 shows a pair 500 of galvo scanners.

FIG. 6 shows a conventional system 600 that is improved using portionsof the teaching of the present invention.

FIG. 7 is a block diagram of a low-cost sensor/laser-pointer system 700.

FIG. 8 is a partially enlarged block diagram of low-costsensor/laser-pointer system 700.

FIG. 9 is a partially enlarged block diagram of low-costsensor/laser-pointer system 200.

FIG. 10 is a perspective diagram of a proof-of-conceptsensor/laser-pointer system 1000.

FIG. 11 is a block diagram of a proof-of-concept sensor/laser-pointersystem 1100.

FIG. 12 is a graph 1200 of attenuation versus wavelength for one type ofoptical fiber.

FIG. 13 is a block diagram of an output aperture 1300 and a laser-beampath from a fiber bundle.

FIG. 14 is a graph 1400 of attenuation versus wavelength for one type ofoptical fiber.

FIG. 15 is an end view of a portion of a conventional fiber bundle 1500that is used in some embodiments.

FIG. 16 is an end view of a portion of a fused fiber bundle 1600 that isused in some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Although the following detailed description contains many specifics forthe purpose of illustration, a person of ordinary skill in the art willappreciate that many variations and alterations to the following detailsare within the scope of the invention. Accordingly, the followingpreferred embodiments of the invention are set forth without any loss ofgenerality to, and without imposing limitations upon the claimedinvention.

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof,and in which are shown by way of illustration specific embodiments inwhich the invention may be practiced. It is understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from the scope of the present invention.

The leading digit(s) of reference numbers appearing in the Figuresgenerally corresponds to the Figure number in which that component isfirst introduced, such that the same reference number is used throughoutto refer to an identical component which appears in multiple Figures.Signals and connections may be referred to by the same reference numberor label, and the actual meaning will be clear from its use in thecontext of the description.

FIG. 1 is a diagram of a sensor/laser-pointer system 100 thatillustrates a one-to-one correspondence between the receiver apertureand transmitting fiber according to some embodiments of the invention.Low-cost sensor/laser-pointer (e.g., in some embodiments, one useful forIRCM) system 100 of some embodiments of the present invention uses adistributed aperture to provide the beam steering typically conductedwith a two- or three-axis precision gimbal. As shown in FIG. 1, thebeam-steering system 121 of the present invention is the transmitteranalog to a focal-plane missile-warning imager or sensor 111 (in someembodiments, imaging sensor 111 includes a camera and lens mounted onthe outside of the platform, with a signal wire or cable running signalsto a centrally located processor). In the sensor/laser-pointer system100, the Missile Warning Sensor (MWS) sensor 110 includes a collectionlens (not shown) that directs the ultraviolet (UV), visible or infrared(IR) light from an incoming missile or other object onto an arraydetector 112, where each resolution element (e.g., element 113) in thedetector defines a solid angle in the MWS system's field-of-regard. Thesensor signal is passed on wire 110 to an image processor 240 (see FIG.2). The beam-steering output method and apparatus 120 of the presentinvention essentially uses the same concept in reverse. In someembodiments, using a multiple-element fiber bundle 122, laser power isdirected into a particular fiber 123 (indexed to a pixel 113 on thesensor 110 (e.g., an MWS, in some embodiments), resulting in the laserenergy being directed outward to the same solid angle as the radiationreceived from the threat or other object. In some embodiments, there isa one-to-one correspondence between resolution elements in the receiverarray 111 and fibers in the transmitter array 121. Thus, in someembodiments, there is a one-to-one correspondence between each of aplurality of spots on the detector array 112 in the receiver aperture111 and a corresponding one of a plurality of transmitting fibers in thearray 122 making up the fiber bundle in the transmitting aperture 121.

In some embodiments, the one-to-one relationship is ensured by bundlingand/or affixing to one another a plurality of fibers, and then cleavingthe bundle, thus ensuring that each fiber end at one cleaved endcorresponds exactly to that fiber at the other cleaved end. In someembodiments, a “folded” or “looped” (i.e., looped to some bend radiusthat will not break the fiber) middle point (i.e., somewhere between thetwo ends of the fiber, typically but not necessarily in the exactmiddle) of fiber is threaded from each external aperture on the vehicle(e.g., a helicopter) or other mobile or fixed platform, to the locationof receiver 240/transmitter 220 (see FIG. 2), thus providing two fibers(a transmit fiber connected to a receive fiber at the loop or foldpoint) from each external aperture to receiver 240/transmitter 220. Onceall the fibers are connected from their respective external apertures totheir folded ends at the receiver/transmitter, the folded ends arebundled to, e.g., a square cross section, and cleaved to obtain areceive-end bundle and a transmit end bundle, each bundle having fiberends in a mirror-corresponding configuration (i.e., once cut, the fibersacross any given row that are left-to-right on the receiver willcorrespond to those fibers in a right-to-left order on the same row ofthe transmitter). In other embodiments, a large number of fibers can bewound (e.g., around a large circular form) to a length at least as longas the longest fiber routing in the vehicle (e.g., 2 meters, in someembodiments). Once all the fiber loops are wound, the fibers at onepoint along the circular form are gathered into a bundle (e.g., onehaving a square cross-section area), and are cleaved to obtain a receiveend bundle and a transmit end bundle, each having fiber ends in amirror-corresponding configuration (i.e., once cut, the fibers acrossany given row that are left-to-right on the receiver will correspond tothose fibers in a right-to-left order on the same row of thetransmitter). At some midpoint between the transmit end and the receiveend, each fiber is separately routed to its respective external apertureon the vehicle and cleaved at that point to form one fiber that goes tothe receive end bundle, and another fiber that goes to amirror-corresponding point on the transmit end bundle.

Fiber bundles are commonly used in medical endoscopes, where in someembodiments 30,000 fibers are bundled to create a flexible imagingcable. Recent developments (e.g., at the Naval Research Laboratory) havedeveloped low-loss mid-infrared-transmitting fibers, (e.g.,chalcogenide-glass fibers), and commercial manufacturers have fabricatedmid-IR fibers into multi-element bundles.

In some embodiments of this design, the receiver and transmitterapertures are co-located and coupled rigidly to a common structure.Thus, any flexing in the platform structure will not lead tomisalignment between the receiver and the transmitter.

FIG. 2 is a system block diagram for a low-cost sensor/laser-pointersystem 200. In some embodiments, a fiber bundle and transmit lens (orother transform optics configured to transform light from a spatiallocation at the end of the fiber bundle into a beam at a selecteddirection, i.e., azimuth angle and altitude angle) is matched to eachMWS sensor, and, in some embodiments, a plurality (e.g., four) sensorsare typically used to cover a helicopter or other mobile platform (insome embodiments, the present invention is particularly useful for aplatform with a low heat signature). A single centrally mounted laser inthe helicopter (or other platform) can address all MWS sensed locationsby coupling the laser beam into a specific fiber element in a bifurcatedbundle. In some embodiments, a conventional scanning galvanometer isused to steer the laser beam into the various fibers of the transmitbundle. This small-field-of-view with precision motion is ideal for thegalvanometers, which, in some embodiments, can cost less than $6,000.Further cost reduction is achieved by using only the coarsethreat-location data directly from the MWS sensor and eliminating thefine-track mid-infrared camera. Elimination of the gimbal pointer andtracking camera can provide $500,000-$800,000 cost saving pertransmitter assembly.

FIG. 1 shows there is a one-to-one correspondence between a resolvablespot on the detector array in the receiver aperture and a transmittingfiber in the array making up the fiber bundle in the receiver aperture.

FIG. 2 shows a distributed-aperture laser-pointer system 200 (in someembodiments, one that is used for IRCM) that uses coarse-tracking datafrom the image sensors (e.g., MWS) to establish threat coordinates and asingle scanner (or other form of fiber selector) to point the outputlaser beam (e.g., a jamming beam, in some embodiments) in the requireddirection. Significant cost reductions can result from eliminatingmultiple beam pointers and fine-track cameras. In some embodiments,system 200 includes a plurality of image-sensor systems 210, eachpointing in a different direction to obtain image data 215 from variousparts of the environment, which is sent to and processed by imageprocessor 240. In some embodiments, image processor 240 also generateslaser control (to power the lasers), modulation control (to modulate thelaser beam, if desired, either by modulating power to the lasers or bymodulating the beam from the lasers (e.g., using an acousto-opticmodulator (AOM)), and direction control (to point the laser beam in thedirection of a sensed object), wherein these controls are sent assignals to laser-pointer unit 220. In some embodiments, laser-pointerunit 220 includes at least one mid-IR laser 221, beam-shaping optics 222(in some embodiments, beam-shaping optics 222 is merged with one or moreof the X-Y deflection mirrors of fiber selector 223). The laser beam isdirected into the end of one of the fibers in one of the one or morefiber bundles 125, wherein each fiber bundle 125 is routed along orthrough the platform to a corresponding transmit optics 120, wherein thefar ends of the fibers and the transmit optics are configured to formone or more output laser beam(s) in various directions (e.g., someembodiments use four bundles 125, four transmit optics units 120 todirect the laser beam(s) to one or four quadrants).

Although, in some embodiments, the laser would be capable of producingoutput with very narrow solid angles, the divergence of the laser mustbe increased to fill the solid angle typical of the MWS imaging sensor,to ensure that the target identified within an imaging-sensor pixel orcell (e.g., an MWS cell) is illuminated. Because of the increased laserdivergence, the power of the laser must be increased, to provide asufficient jamming/laser-signal strength (J/S) ratio. For certainplatforms such as low-signature helicopters, this approach is feasibledue to the relatively low radiant intensity needed to provide sufficientlaser-signal strength (J/S ratio) to cause the missile to opticalbreak-lock or other desired effect on the target object. Beam shaping isused in some embodiments to propagate a flat-top intensity profile,which improves the efficiency and maintains the laser-power requirementat a manageable level.

FIG. 3 is a block diagram of efficiencies (losses) that illustrateslaser-power scaling, accounting for the various loss elements in theoptical train in one embodiment. For example, choosing a one-watt laserand a beam divergence of one degree, the scaling shows that a far-fieldoutput radiant intensity of 1.67 kW/steradian per W of input power isproduced, in some embodiments. Any arbitrary laser power could be usedin various embodiments. In some embodiments, one or more mid-IRoptically pumped semiconductor lasers (OPSL) 221 output a given power(e.g., 1 watt) into beam-combining unit 326 having an efficiency of 90percent, thus transferring about 0.9 W to beam-shaping unit 222 alsohaving an efficiency of 90 percent, thus transferring about 0.81 W toscanning unit 223, which has an efficiency of 95 percent. About 0.77 Wof laser power are transferred one fiber (e.g., a 10-meter fiber havinga 250-micron-diameter core) within fiber bundle 125, the fiber having anefficiency of 80 percent, thus transferring about 0.62 W to transmitoptics 331 (e.g., optics that forms an output beam of suitabledivergence (e.g., one degree, in some embodiments) to achieve thedesired fill factor. If the transmit optics 331 have an efficiency of 90percent, they transfer about 0.55 W to the output beam (e.g., a beamhaving a fairly uniform “top-hat” power-distribution shape in the farfield), of which about 0.39 W is within the area of regard. The fiberlosses, even in the mid-IR wavelengths, are very low since large-corefibers are used and the losses due to far-field uniformity are low sincea uniform profile is generated in the far field. Researchers at the AirForce Research Lab (AFRL) have demonstrated laser power greater than 10W with an optically pumped semiconductor laser (OPSL), which could beused in some embodiments (see, e.g., A. P. Ongstad et al., “Performancecomparison of optically pumped type-II midinfrared lasers,” J. Appl.Phys. 98, 043108 (15 Aug. 2005) (7 pages), which compared theperformance of three optically pumped, type-II quantum well lasers withdiffering quantum well (QW) confinement. One of the active regionsemphasized hole confinement, another emphasized electron confinement,while the third incorporated both electron and hole confinements. In allcases the wells were inserted in a thick In_(x)Ga_(1-x)As_(y)Sb_(1-y)waveguide/absorber region. The lasing wavelengths at 84 degrees K. were2.26, 3.44, and 2.37 microns, respectively. The maximum peak outputpowers and differential quantum efficiencies η at 84 K. were similar forthe hole-well and W lasers (about 13 W, η≈0.55), but significantlyreduced in the electron-well-only laser (2.3 W, η=0.14).).

FIG. 3 shows that the distributed-aperture laser-pointer concept (insome embodiments, one useful for IRCM) with a laser power of 1 W and onedegree beam divergence (the moon is about one-half degree in width, sothis 1-watt laser-input embodiment projects about 0.39 watts into afar-field spot about twice the moon's diameter) will achieve a radiantintensity of 1.67 kW/steradian in the far field. In some embodiments,other laser input powers scale proportionately, so a laser is selectedhaving the power needed to obtain a desired radiant intensity.Fiber-coupling losses are very low since some embodiments use alarge-core fiber, and losses due to the far-field uniformity are lowsince some embodiments generate a uniform profile in the far field.

In some embodiments, the invention could enable the hardware cost of anIRCM system for low-signature helicopters to be reduced to 1/10^(th) thecost of current IRCM systems. FIG. 4 shows the overall system conceptfor a low-cost distributed-aperture beam-steering laser-pointer (IRCM)beam-steering system 400. The invention could enable the hardware costof a laser-pointer system for certain platforms (e.g., for low-signaturehelicopters) to be reduced to about ten percent of the cost of currentlaser-pointer systems. In some embodiments, a plurality (e.g., four, insome embodiments) of sensors 410 (e.g., solid-state cameras or othersuitable imager for one or more wavelengths of interest) each points ina different direction from the platform (e.g., an aircraft) and providedirection parameters to laser/scanner unit 420 that outputs a laser beamto one or more fibers of a plurality of fiber bundles (e.g., four, insome embodiments), wherein one or more fibers outputs its light througheach transmit lens 331 (in some embodiments, each transmit fiber's farend has its own lens to point its beam in a particular chosen directionwith a chosen beam divergence). In some embodiments, system 400 includesa plurality of image sensors 410 (e.g., cameras having a suitablewavelength sensitivity, speed and field-of-view) and a correspondingnumber of transmit lenses 331 each coupled to a respective fiber bundle125. In some embodiments, signals are coupled from the image sensors 410to mid-IR-laser/scanner system 420, which then generates and modulates alaser signal and directs the laser signal to a selected one of thefibers in fiber bundles 125 in order that an output beam is projectedfrom its transmit lens 331 to the desired direction (e.g., a selectedazimuth and altitude corresponding to the sensed energy (which could beUV, visible, and/or IR)).

FIG. 5 shows a pair 500 of galvo scanners that are used in someembodiments to direct the output laser beam using mirrors for fiberselector 223 (in an X-direction using mirror M3 on one scanner 501 andin a Y-direction by mirror M2 on the other scanner 502) into the end ofa selected fiber in a fiber bundle (e.g., bundle 122 of FIG. 1). In someembodiments, M-series galvo scanners from GSI Lumonics Inc. are used(e.g., see www.gsig.com/scanners/optical_spec.html or contact GSI Group,39 Manning Rd., Billerica, Mass. 01821). In some embodiments, the mirroron one or more of the scanners also provides a focussing function forthe outgoing laser beam.

Another potential system cost saving can be obtained from fiber couplingthe mid-IR laser to the pointer/tracker of a conventionallaser-pointer-tracker system. Fiber coupling allows the Mid-IR laser tobe isolated from the helicopter platform's vibration, thereby reducingthe engineering required to harden the laser. Isolating the laser fromvibration should also reduce the lifecycle costs by improving thereliability. The most significant cost savings, however, is presentwhere multiple pointer trackers were required to provide adequateprotection, with a single remotely located laser being coupled into anypointer tracker. Using a single laser for all bundles precludes orcomplicates the option of pointing laser beams at multiple objects(countering multiple threats) simultaneously, and in some embodiments,this level of complexity can add cost to the system. In someembodiments, multiple threats or other objects are addressed serially(pointed to in a sequential manner), using a single laser. In otherembodiments, multiple lasers are provided in order to simultaneouslyaddress multiple threats or other objects.

FIG. 6 shows a conventional system 600 that is improved using portionsof the teaching of the present invention. In some embodiments, system600 includes a plurality of image sensors 110 attached to one or morestructures of the platform, which passively (i.e., without transmittingany illumination) detect IR light from a scene, and transmit sensor-datasignals 115 to image processor 240. Based on sensing an object ofinterest, processor 240 generated laser-power-control andmodulation-control signals to mid-IR laser unit(s) 621 which directlaser energy to the beam-pointer portion of pointer/tracker unit(s) 620,which then direct that laser energy into one or more output laser beams.In some embodiments, passive IR light from the scene is gathered bytracker portion(s) of pointer/tracker unit(s) 620 into tracking cameras641, which provide fine-tracking data to image processor 240, in orderthat it continues to provide pointer-control signals to pointer/trackerunit(s) 620 to keep the output laser beams on the desired object.

FIG. 7 is a block diagram of a low-cost sensor/laser-pointer system 700.In some embodiments, system 700 includes a plurality of fiber bundles705 for receiving scene light from respective receiving optics units(e.g., unit 711 pointing downward relative to the platform, unit 712pointing behind, unit 713 pointing left, unit 714 pointing upward, unit715 pointing ahead, and unit 716 pointing right) and a plurality offiber bundles 706 for transmitting laser light through respectivetransmitting optics units (e.g., unit 721 pointing downward relative tothe platform, unit 722 pointing behind, unit 723 pointing left, unit 724pointing upward, unit 725 pointing ahead, and unit 726 pointing right).In some embodiments, the ends of all of the receiving fiber bundles 705are imaged using a single camera 718 connected to imaging system 719 ofimaging unit 710, which provides image data to image processor 740,which then generates laser power control, modulation control, andpointing-direction control to transmitting unit 720, which, in someembodiments, has a laser 221, beam shaping 222, and steering 223 (seeunit 220 of FIG. 2), and outputs its laser energy to the end of one ofthe fibers in fiber bundles 706. In some embodiments, if a plurality oftarget objects are simultaneously identified by imaging unit 710, theseobjects are sequentially pointed at by the output laser beam.

FIG. 8 is a partially enlarged block diagram of low-costsensor/laser-pointer system 700 that was shown in FIG. 7. A close-upview of the interior or central ends of a subset 727R of the transmitfibers 727 (here, numbered 1 to 61, where fibers 35, 36, and 37 areshaded with vertical, horizontal, and diagonal lines, respectively), anda smaller view of the exterior or far ends of subset 728R are shown nextto right-hand transmit lens 726. Similarly, a close-up view of theinterior or central ends of a subset 717R of the receive fibers 717(here, numbered 1 to 61 and a mirror image of the transmit fibers 727R,where fibers 35, 36, and 37 are shaded with vertical, horizontal, anddiagonal lines, respectively), and a smaller view of the exterior or farends are shown next to right-hand transmit lens 726. Suppose a movingobject is successively seen at points A, B, and C at the bottom of thediagram, and is imaged to the ends of three receive fibers by lenssystem 716, which light is carried by the fibers to the interior ends717R of fibers 35, 36, and 37 (shaded with vertical, horizontal, anddiagonal lines, respectively, these fiber ends are between fiber end 34and fiber end 38) and imaged by imaging unit 710 and processed byprocessor 740. Processor 740 controls the laser output to be sent firstto the end of vertical-line-shaded fiber 35, then to the end ofhorizontal-line-shaded fiber 36, and then to the end ofdiagonal-line-shaded fiber 37, and these transmit fibers carry the laseroutput to transmit lens 726 which transforms the light at a spatiallocation on the end of the fiber bundle to an angular direction andforms an output laser beam that essentially tracks the object as itmoves from A to B to C. In some embodiments, processor 740 determinesthe direction and rate of movement of the object, and thus at leastpartially anticipates where the object will be in order to move theoutput laser beam more quickly to the appropriate fiber and better trackthe object with the laser beam.

FIG. 9 is a partially enlarged block diagram of alternative low-costsensor/laser-pointer system 200. System 200 is similar to system 700 onthe transmit side, but rather than a centrally located camera and afiber bundle bringing the image to a central location on a fiber bundle,the camera 918 is remotely located (e.g., having its lens on or near theexterior of the platform next to transmit lens 726), with an electricalwire (or a single optic fiber) 915 carrying image data (rather than theimage itself, as with a fiber bundle) to the imaging unit 919. Otheraspects of system 900 are as described for FIG. 7 and/or FIG. 2.

FIG. 10 is a perspective diagram of a proof-of-conceptsensor/laser-pointer system 1000. In some embodiments, a person (user99) points a hand-held laser 1010 that outputs a green laser beam 1011onto a screen. A camera attached to processor 1040 locates the greenspot on the screen and controls a red laser beam output to track andfollow the green spot. In some embodiments, green and red are chosen tomake more apparent the functioning of the system. In some embodiments,user 99 uses a plurality of green lasers to simulate a plurality ofobjects to sense, analyze and track. In some embodiments, this system isused in development and testing of the algorithms and hardwareconfiguration of the system, since the visible light laser spots make iteasier to debug the system than using infrared objects and trackingbeams.

FIG. 11 is a block diagram of a proof-of-concept sensor/laser-pointersystem 1100 (e.g., one implementation of system 1000 for someembodiments). In some embodiments, system 1100 includes a wavelengthfilter 1116 for receiving scene light and passing the green but not thered portions, a receiving lens 1117 and camera 1118 that passes an imagesignal to imaging unit 1110 (e.g., a personal computer with BeamView(from Coherent Inc., 5100 Patrick Henry Drive, Santa Clara, Calif.95054, or other suitable hardware/software), which provides image datato image processor 1140, which then generates pointing-direction controlto transmitting unit 1120, which, in some embodiments, has a laser 1121,beam shaping 1122, and steering 1123 (similar to unit 220 of FIG. 2),and outputs its laser energy to the near end 1127 of one of the fibersin fiber bundle 1106. The remote end 1128 of the fiber bundle 1106projects its light through output/transmitting lens 1126 into a beam1102 that points in the direction of the spot reflected into receivedlight 1101. In some embodiments, if a plurality of target objects aresimultaneously identified by imaging unit 1110, these objects aresequentially pointed at by the output laser beam.

FIG. 12 is a graph 1200 of attenuation versus wavelength for one type ofoptical fiber. FIG. 12 shows that certain chalcogenide-glass fiberstransmit have low loss over a large portion of the mid-IR wavelengthrange from 2.2 μm to 4.9 μm, with the exception of a single absorptionfeature between 3.95 and 4.2 μm.

FIG. 13 is a block diagram of an output aperture 1300 and a laser-beampath from a fiber bundle end 728 of a fiber bundle 706. In someembodiments, multimode fibers are used in order to obtain a uniformintensity distribution over most of each fiber end (e.g., from top (A),middle (B) and bottom (C)). This light passes through transform lens726, and generates an Airy function intensity distribution 1350 at atransform plane (at a front focal distance f from the lens) and forms asubstantially uniform top-hat intensity distribution 1351 in the farfield.

FIG. 14 is a graph 1400 that shows the effect of increasing theparameter β (discussed more below) on the shape of the output-intensityprofile (Γ is normalized intensity and α is normalized radius). It canbe seen that with β>32 the output-beam-intensity profile is essentiallya flat top. This puts a lower limit on the fiber-core diameter ofD_(f)>85 microns. If D_(f)=100 μm is chosen then the configurationparameter is V=18.8 and the number of modes the fiber can carry isM=178.

FIG. 15 is an end view of a portion of a conventional fiber bundle 1500that is used in some embodiments. In some embodiments, when cylindricalfiber ends are tightly bundled, they form a hexagonal pattern with openinterstitial space between each triplet of fibers. Note that in someembodiments, very large cores and very thin cladding is used in order todirect as much laser light into the fiber as possible. The round shape,even for multimode fibers, does not promote uniform intensitydistribution as well as the configuration of FIG. 16.

FIG. 16 is an end view of a portion of a fused fiber bundle 1600 that isused in some embodiments. In this configuration, the fibers are fusedsuch that each fiber forms a hexagonal shape that is tightly packedagainst its neighbors. This increases the amount of laser lighttransferred into the fibers (since little is lost in interstitialspaces), as well as providing additional reflection surfaces to make theintensity distribution more even.

System-Design Considerations

The most significant losses are in the fiber coupling and the far-fieldprofile. The OPSL output is diffraction limited (DL) in one directionand 4 to 5 times DL (four to five times diffraction limited) in theorthogonal direction. In order to produce the required output divergencein the far field, assuming a 12.4-mm output aperture, some embodimentsare limited to a beam quality of two to three times DL. Thus, there is apower loss in one dimension when coupling into the fiber. The loss dueto the far-field profile is a result of the non-uniform far-fieldprofile. If a Gaussian distribution is produced in the far field with a1/e² diameter of 2 mrad, then the intensity at the edge of the field isonly 23% that of a uniform distribution of the same size. Nonetheless,even with these inefficiencies the laser power required to produce aradiant intensity of 1.67 kW/steradian is less than 1 W.

Alternative-System Concept

FIG. 6 shows a laser-pointer system 600 of some conventionalembodiments. Multiple pointer trackers will probably be required toachieve adequate protection, given the large field-of-regard. System 600includes a plurality of image sensors 110 that provide image data toimage processor 240, which in turn provides pointing parameters to beampointers of pointer/tracker units 620 that point laser beams coupledfrom lasers 621 onto one or more remote objects. Tracking cameras 641track the objects providing feedback to the pointers to keep thempointing in the desired direction(s). In a modification of conventionalsystem 600, the system cost could be reduced by fiber coupling the laserto multiple pointer trackers, thereby reducing the number of lasersrequired. Similarly, one alternative embodiment of the present invention(depicted in FIG. 7) eliminates one or more of the multiple pointertrackers by fiber coupling the light from a single scanner to multiplelocations on the helicopter platform. Further cost reductions areobtained in some embodiments by eliminating the fine-track cameras andrelying on the coarse-track data from the missile-warning or other imagesensors to establish the threat's or other object's coordinates. Thelaser-beam divergence and power can be increased to match the precisionof the coarse-track data to assure the laser signal (e.g., jammingsignal) intercepts the object (e.g., incoming missile or other threattarget). The schematic for such a system is shown in FIG. 7.

The key to understanding this concept is that there is a one-to-onecorrespondence between resolution elements in the receiver and fibers inthe transmitter, as illustrated in FIG. 8. FIG. 8 shows a one-to-onecorrespondence between a resolvable spot on the detector array in thereceiver aperture and a transmitting fiber in the array making up thefiber bundle in the transmitter aperture. Each resolution element in thedetector defines a solid angle in the MWS field-of-regard. If a threatis detected within that resolution element the laser power is directedinto a particular fiber that transmits into that same solid angle. Onekey aspect of this design is that the receiver and transmitter aperturesare co-located and coupled rigidly to a common structure. Thus, anyflexing in the platform structure will not lead to misalignment betweenthe receiver and transmitter.

In some embodiments, the divergence of the laser is increased to fill asolid angle equivalent to one pixel of the MWS. The power of the lasermust be increased, as well, to provide a sufficient jam signal.Fortunately, because the beam can be many times diffraction limited andstill fall within this solid angle, a more uniform profile can betransmitted into the far field. FIG. 3 shows that a 1-W laser generatesa far-field radiant intensity of 1.67 kW/steradian if a one-degree beamdivergence is chosen. Researchers at AFRL (e.g., see the A. P. Ongstadet al. article cited herein) have demonstrated output powers of 14 W at3.5 microns from an OPSL, which would correspond to 11 W at 4.5 microns.Fiber-coupling losses are assumed to be very small since in someembodiments the beam is coupled into a fiber having a large-mode-areacore (e.g., one having a core of about 250 microns diameter, in someembodiments) fiber.

The top-hat profile is created in the far field by generating a uniformintensity at the end of the fiber and then imaging the end of the fiberbundle into the far field. The key is in producing a uniform intensityover the end of a fiber in a way that is not affected by varying thefiber-bundle handling or environment. Nominally, the OPSL output willnot fill all of the fiber modes, and the fiber will probably not be longenough to allow sufficient mode mixing. Applying mechanical stress orshaping the fiber (non-circular cross section), perhaps over asubsection, will alter the mode-coupling properties and can be used tovary the output profile. Shaping the injected beam (changing theintensity or phase profile) such that it fills all of the fiber modescan also be used to improve the output uniformity. However, since thecoupling between modes is determined largely by the defects in thefiber, and mid-IR fiber was developed only recently, the best method forgenerating a uniform intensity will have to be determined empirically.

Fiber-Bundle Demonstration Experiment

The fiber-bundle experiment shown in FIG. 10 and FIG. 11 sends out a redlaser output beam that is pointed to track or follow a green spotprojected from a green laser pointer onto a wall or screen. In someembodiments, the red track beam steps from one location to the next (dueto the spacing, beam divergence, and pointing direction of the variousfibers) as the beam is switched from one fiber to the next in responseto the continuous motion of the green-laser-pointer spot. Using visiblewavelengths eases issues with diagnostics and makes the operation of thesystem even more visible (apparent to observers). The field-of-regard inthe experiment, in some embodiments, is 30 degrees horizontal andvertical. The 1-degree divergence of the track beam would be maintainedas is present in some embodiments of the invention. Thus, the fiberbundle would contain about nine hundred fibers in a nested square array.In other embodiments, other widths of field of regard, other solid-angledivergences for the individual beams, and other numbers of fibers can beused to suit the requirements of a particular installation.

The block diagram of a system 1100 for the experiment is shown in FIG.11. The upper half of the system provides a lab version of an imagingsensor 710 and the image processor 740. The lower half of FIG. 11provides the track laser, the mirrors and lenses for injecting the beaminto the fiber bundle, the fiber bundle itself, and the output lens.

Mid-IR Fiber-Bundle Design

Various embodiments of the invention use various wavelengths for thelasers. In some embodiments, mid-IR wavelengths (e.g., between about 2microns and about 5 microns) are used. In some embodiments, thedistributed-aperture approach of the present invention for a low-costpointer tracker has a mid-IR fiber bundle that serves to distribute thelaser energy to transmit apertures co-located with the imaging sensors.The design of the fiber bundle can have a significant impact on theefficiency of the system as a result of fiber-coupling losses becausethe fiber bundle affects the far-field intensity distribution. Theefficiency with which laser light is coupled to the target determinesthe size, weight, and cost of the laser, so it is important to considerthe fiber-bundle design tradeoffs carefully.

In this section the objectives of the fiber-bundle design for someembodiments are laid out and the design considerations are describedthat result in the choice of important design parameters. Methods arealso described for generating uniform spatial intensity at the end ofthe fiber and coupling the laser light into and out of the fiber bundle.

Design Objectives

The design parameters for some embodiments of the fiber bundle withtypical values for some embodiments are listed in Table 2. These valuesare not derived from a specific set of requirements; rather they are anestimate of what is required from the distributed-aperture system to bean effective laser-pointer system for some applications.

TABLE 2 Example parameters for the fiber bundle, in some embodiments:Design Parameter Value Divergence of laser output 1° FW Uniformfar-field beam distribution I = I_(mean) +/− 10% within 1° cone Powerwithin the output divergence >70% cone Match the receiverfield-of-regard 90° cone (FOR) Minimize low-intensity areas in the I <90% of I_(mean) in < 15% of FOR FOR Limit coupling and absorption losses<20%

Fiber-Bundle Design

The characteristics of the light exiting the bundle are determined bothby the parameters of the individual fibers and those of the fiberbundle. The properties of the fibers used in some embodiments are givenin Table 3, and the wavelength-transmission range is shown in FIG. 12.

TABLE 3 In some embodiments, the fiber bundle is based on the propertiesof low-loss chalcogenide glass fibers, as follows: Parameter ValueAttenuation: <0.2 db/m Diameter (D_(f)): Free design parameter (Corediameters ranging from 50 μm to 500 μm are used in various embodiments,however smaller-core or larger-core fibers are used in otherembodiments.) Cladding thickness: Free design parameter (Attenuationwill increase with thinner cladding.) Numerical aperture 0.20 (NA):Length: <5 m Damage limit: 1.1 GW/cm²

Achieving Uniform Intensity at the Fiber End

To obtain a uniform or top-hat profile in the far field requiresbeginning with a fiber that has a uniform intensity profile over thecore, and transforming that into an Airy-pattern intensity distributionin the near field, as illustrated in FIG. 13 and FIG. 14. Propagation tothe far field transforms the beam back into a uniform intensity profile.

To produce a uniform intensity distribution at the output of the fiberrequires that the fiber core is large enough to support a large numberof transverse modes. The number of modes that a cylindrical fiber cansupport is given by

$M \equiv \frac{V^{2}}{2}$where V is a configuration parameter given by

$V = {\frac{\pi \times \; D_{f}{NA}}{\lambda}.}$In some embodiments, it is also important to keep the diameter of thefiber as small as possible so that the bundle dimensions do not get toolarge. It can be shown (Dickey and Holswade, Laser Beam Shaping Theoryand Techniques, Marcel Dekker, Inc., p 23 (2000)) that the difficulty ofredistributing the energy in a laser beam can be estimated by thedimensionless parameter β where

$\beta = \frac{2\;\pi\; D_{i}D_{o}}{\lambda\; z}$where D_(i) and D_(o) are the input and output beam diametersrespectively. Substituting in the parameters for one embodiment of theinvention gives

$\beta = \frac{2\;\pi\; D_{f}{NA}}{\lambda}$

If β is large the problem follows geometrical theory of beam shaping. Ifβ is small then the problem is dominated by diffraction making itimpossible to redistribute the laser power. FIG. 14 shows the effect ofincreasing the parameter β on the shape of the output-intensity profile(Γ is normalized intensity and α is normalized radius). It can be seenthat with β>32 the output-beam-intensity profile is essentially a flattop. This puts a lower limit on the fiber-core diameter of D_(f)>85microns. If D_(f)=100 μm is chosen then the configuration parameter isV=18.8 and the number of modes the fiber can carry is M=178.

Coupling the Laser into the Fiber

The next question is how the laser light may be injected in such a waythat it occupies the modes. The most straightforward method is to simplycouple the light into the fiber and let coupling between fiber modestransfer light from the initially occupied modes to all of the modes.Unfortunately, this method requires long fibers (>100 m) and theabsorption and scattering losses that would result from propagating overlarger distances in the fiber cannot be tolerated.

Another method of filling the fiber modes is to degrade thebeam-parameter product of the laser light upon injecting it into thefiber such that it fills the fiber beam-parameter product. Thebeam-parameter product of a mid-IR fiber with a 100-μm core is 40mm-mrad. Optically pumped semiconductor lasers (OPSLs) typically havebeam-parameter products of about 25 mm by 10 mm-mrad in the directionsparallel and perpendicular to the emitting junction. Thus, thebeam-parameter product must be degraded by about 1.6 times in onedirection and by four times in the other. Focusing the laser to a spotsize slightly smaller than the fiber core and using an appropriatebinary phase plate (see N. Davidson, R. Ozeri, and R. Baron,“Fabrication of binary phase surface relief optical elements byselective deposition of dielectric layers”, Rev. Sci. Instru., 70, 2,pp. 1245-1247 (1999)) to expand the divergence on the beam such that itmatches the fiber numerical aperture (NA) will degrade thebeam-parameter product. The phase plate reduces the spatial coherence ofthe laser light. For example, in some embodiments, 10-W laser would leadto a peak intensity of <0.5 MW/cm² on the fiber end, well below the 1.1GW/cm² damage limit.

It is reasonable to wonder if speckle due to the interference betweenmodes could result in a non-uniform intensity distribution at the end ofthe fiber. If the bandwidth of the laser light satisfies the followingrelationship

${\Delta\;\lambda} > \frac{\lambda\;{NA}^{2}}{n^{2}V}$the device of the present invention is in the mode-continuum limit wherethe speckle size approaches zero and the modal noise is not an importanteffect. (See, e.g., Mickelson, Alan Guided Wave Optics. Van NostrandReinhold, p 189 (1993).) Assuming a core index of 2.4 gives a lowerlimit for the bandwidth of 1.5 nm. The bandwidths of OPSLs are on theorder of 50 nm, so modal noise will not degrade the far-field uniformitywith these sources; however, a solid-state mid-IR laser would probablyhave speckle problems.

Bundle Configuration

To cover the field-of-regard of the missile-warning sensor the fiberbundle must be composed of a 90×90 matrix of fibers, since each fiberwill have a 1° field of view and the sensor has a 90° field-of-regard.With 8,100 fibers that have 100-μm cores the fiber bundle will have across section of <1 cm². The efficiency due to the fill factor is thefraction of the bundle area made up of the fiber cores. This efficiencydetermines the coverage in the far field, although there will be someoverlap between the fiber images due to the smoothing effects ofturbulence and defocus. In a conventional hexagonal packing patternη_(ff) is given by

$\eta_{ff} = {\frac{\pi}{2\sqrt{3}}\left( \frac{D_{f}}{D_{c}} \right)^{2}}$where D_(f) is the core diameter and D_(c) is the fiber diameter withthe cladding. The first term is due to interstitial areas between fibers(π/2√{square root over (3)}=0.907) and the second term is due to thefinite thickness of the cladding. As shown in FIG. 15, the fibers can bearranged in a conventional hexagonal pattern or fused (as shown in FIG.16) to eliminate the interstitial area. (In some embodiments, the bundlefill factor can be increased by about 10% if the ends are fused toeliminate the interstitial areas.) Another advantage of hexagonal fibersis that the shape results in the injected light being thoroughly mixedso the fiber modes are filled and the output is spatially uniform. Thecorners in the fused fiber bundle may result in additional losses in thefar field due to diffraction losses. Also, fusing can lead to breakagein silica fibers, so it must be determined if sulfide fibers can befused without damaging the fibers.

The cladding thickness affects both the fiber bundle fill factor and thelosses due to light leakage out of the fiber. If a fiber forlong-distance light transport were being designed, the claddingthickness would be made at least 5 times greater than the longestwavelength the fiber would carry to limit losses. As the claddingthickness is decreased the rays striking the cladding at high angles ofincidence will leak out through the cladding and be lost. Light in thehigher-order modes tends to propagate at higher angles, so the highermodes will be the first to be lost. Fortunately, many embodiments of theinvention use fiber lengths less than five meters (5 m) so light leakagelosses should not be too high. Some embodiments select the claddingthickness of 10 μm initially based primarily on the fill-factor issue.

Design-Parameter Summary

The various parameters of the fiber and bundle design have been analyzedin light of a baseline set of requirements and assigned reasonablevalues. With the values selected it appears that it will be possible toproduce a flat-top distribution in the far field, cover the entiremissile-warning sensor field-of-regard, meet efficiency goals, and coverthe field-of-regard while minimizing areas with low radiant intensitydue to cladding and interstitial areas Table 4 summarizes the designparameters for the fiber bundle and describes the effects of scaling theparameter to guide future design tradeoffs.

TABLE 4 Summary of fiber bundle design parameters and the implication ofvarying the values. Parameter Value Scaling Fiber-core 100 μm Increasingdiameter can lead to more diameter (D_(f)): uniform distribution ifpower is distributed in additional modes, Increasing size will increasesize of bundle and optics. Cladding 10 μm Increasing thickness willimprove thickness: transmission for higher order modes, Increasingthickness will increase size of bundle and optics, Increasing sizereduces the far-field coverage by increasing gaps between beams. Fibersin bundle: 8100 Increasing number increases the field-of-regard. Bundlesize: <1 cm² Increasing size increases the size of the optics forcoupling into and out of the bundle. Fiber NA: .27 Increasing wouldfurther complicate design of input and output optics. Input-beam 25 × 10Matches fiber beam parameter product in one parameter mm- direction andmust be increased by 2.5× in product: mrad the other direction to fillthe fiber modes. Bundle end fused Must determine if chalcogenide glassfibers configuration: can be fused, Coverage decreases by ~10% if fiberscannot be fused.

In some embodiments, the present invention provides an apparatus thatincludes a first fiber bundle having a plurality of light-transmittingfibers including a first fiber, a second fiber, and a third fiber, thefirst fiber bundle having a first end and a second end, a laser thatemits laser energy, a processor that generates direction-controlinformation, a fiber selector that is operatively coupled to theprocessor and based on the direction-control information, is configuredto direct the laser energy into the first fiber at the first end of thefirst fiber bundle during a first time period, and transform opticslocated to receive the laser energy from the second end of the firstfiber bundle and configured to form an output beam of the laser energyfrom the first fiber in a first selected direction of a plurality ofdirections during the first time period.

Some embodiments further include a modulator that modulates an intensityof the laser energy according to a predetermined pattern. In someembodiments, the modulator is a controller that controls power to thesource laser. In some embodiments, these provide amplitude modulation.

Some embodiments further include a sensor operatively coupled to receiveelectromagnetic radiation from a scene and to transmit sense informationto the processor based on the received electromagnetic radiation, andwherein the processor is configured to generate the direction-controlinformation based on the sense information.

In some embodiments of the apparatus, the sense information includesinformation useful for determining a first direction toward a locationof a first moving object during the first time period, wherein the firstselected direction of the output beam of the laser energy is the firstdirection toward the location of the first moving object during thefirst time period, wherein the sense information includes informationuseful for determining a second direction toward a location of the firstmoving object during a second time period, wherein the fiber selector,based on the direction-control information, is configured to direct thelaser energy into the second fiber at the first end of the first fiberbundle during the second time period and the transform optics isconfigured to form an output beam of the laser energy from the secondfiber in a second selected direction of the plurality of directionsduring the second time period, and wherein the second selected directionof the output beam of the laser energy is the second direction towardthe location of the first moving object during the second time period.

In some embodiments of the apparatus, the sense information includesinformation useful for determining a third direction toward a locationof a second moving object during a third time period, wherein the fiberselector, based on the direction-control information, is configured todirect the laser energy into the third fiber at the first end of thefirst fiber bundle during the third time period and the transform opticsis configured to form an output beam of the laser energy from the thirdfiber in a third selected direction of the plurality of directionsduring the third time period, and wherein the third selected directionof the output beam of the laser energy is the third direction toward thelocation of the second moving object during the third time period.

Some embodiments further include a second fiber bundle having aplurality of light-transmitting fibers including a first fiber, a secondfiber, and a third fiber, the second fiber bundle having a first end anda second end, transform optics located to receive the electromagneticradiation from the scene and to direct electromagnetic radiation fromeach of a plurality of different directions into a corresponding one ofthe plurality of fibers in the second fiber bundle at the second end ofthe second fiber bundle and wherein the second end of the second fiberbundle is configured to form a pattern of electromagnetic radiationcorresponding to the scene, and wherein the sensor includes a camerathat obtains an image of the second end of the second bundle, in orderto determine a direction to an object in the scene.

Some embodiments of the apparatus further include transform optics(e.g., a lens) located to receive the electromagnetic radiation (e.g.,UV, visible, or IR light) from the scene and to direct electromagneticradiation from each of a plurality of different directions into acorresponding one of the plurality locations on the sensor, wherein thesensor includes a camera that obtains an image of the scene, in order todetermine a direction to an object in the scene.

In some embodiments, the laser is operated to output IR laser light at awavelength greater than 2 microns and in a transmission window of theatmosphere.

In some embodiments, the sensor includes a missile-warning sensor (MWS)on an aircraft, and the apparatus is part of a countermeasures system onan aircraft intended to protect the aircraft from heat-seeking missiles.

In some embodiments, the information detected by the MWS includesinformation useful for determining a first direction from the aircrafttoward a location of a first missile during the first time period,wherein the first selected direction of the output beam of the laserenergy is the first direction toward the location of the first missileduring the first time period, wherein the sense information includesinformation useful for determining a second direction from the aircrafttoward a location of the first missile during a second time period,wherein the fiber selector, based on the direction-control information,is configured to direct jamming laser energy into the second fiber atthe first end of the first fiber bundle during the second time periodand the transform optics is configured to form an output beam of thejamming laser energy from the second fiber in a second selecteddirection of the plurality of directions during the second time period,and wherein the second selected direction of the output beam of thelaser energy is the second direction toward the location of the firstmissile during the second time period.

In some embodiments, the information detected by the MWS includesinformation useful for determining a first direction from the aircrafttoward a location of a first missile during the first time period,wherein the first selected direction of the output beam of the laserenergy is the first direction toward the location of the first missileduring the first time period, wherein the sense information includesinformation useful for determining a second direction from the aircrafttoward a location of a second missile during a second time period,wherein the fiber selector, based on the direction-control information,is configured to direct jamming laser energy into the second fiber atthe first end of the first fiber bundle during the second time periodand the transform optics is configured to form an output beam of thejamming laser energy from the second fiber in a second selecteddirection of the plurality of directions during the second time period,and wherein the second selected direction of the output beam of thelaser energy is the second direction toward the location of the secondmissile during the second time period.

Some embodiments further include a second fiber bundle having aplurality of light-transmitting fibers including a first fiber, a secondfiber, and a third fiber, the second fiber bundle having a first end anda second end, the second fiber bundle directed toward a separate area ofspace than the first fiber bundle, wherein the fiber selector isoperable to switch laser energy to one of a plurality of fibers of thefirst and second fiber bundles, and additional transform optics locatedto receive the laser energy from the second end of the second fiberbundle, where both transform optics are configured to form an outputbeam of the laser energy from the respective fiber bundles, each fiberbundle operable to access a different angular region of space.

Another aspect of the invention, in some embodiments, is a method thatincludes providing a first fiber bundle having a plurality oflight-transmitting fibers including a first fiber, a second fiber, and athird fiber, the first fiber bundle having a first end and a second end,generating direction-control information, based on the direction-controlinformation, directing laser energy into the first fiber at the firstend of the first fiber bundle during a first time period, forming anoutput beam of the laser energy from the second end of the first fiberbundle, and steering the output beam of the laser energy from the firstfiber in a first selected direction of a plurality of directions duringthe first time period.

Some embodiments of the method further include modulating an intensityof the laser energy according to a predetermined pattern.

Some embodiments of the method further include receiving electromagneticradiation from a scene, and generating the direction-control informationbased on the received electromagnetic radiation.

Some embodiments of the method further include generating senseinformation useful for determining a first direction toward a locationof a first moving object during the first time period, wherein the firstselected direction of the output beam of the laser energy is the firstdirection toward the location of the first moving object during thefirst time period, wherein the sense information later includesinformation useful for determining a second direction toward a locationof the first moving object during a second time period, based on thedirection-control information, directing the laser energy into thesecond fiber at the first end of the first fiber bundle during thesecond time period and forming an output beam of the laser energy fromthe second fiber in a second selected direction of the plurality ofdirections during the second time period, and wherein the secondselected direction of the output beam of the laser energy is the seconddirection toward the location of the first moving object during thesecond time period, in order to track the first object.

Some embodiments of the method further include generating senseinformation useful for determining a third direction toward a locationof a second moving object during a third time period, based on thedirection-control information, directing the laser energy into the thirdfiber at the first end of the first fiber bundle during the third timeperiod, and forming an output beam of the laser energy from the thirdfiber in a third selected direction of the plurality of directionsduring the third time period, and wherein the third selected directionof the output beam of the laser energy is the third direction toward thelocation of the second moving object during the third time period, inorder to also track the second object.

Some embodiments of the method further include providing a second fiberbundle having a plurality of light-transmitting fibers including a firstfiber, a second fiber, and a third fiber, the second fiber bundle havinga first end and a second end, receiving the electromagnetic radiationfrom the scene and directing the electromagnetic radiation from each ofa plurality of different directions into a corresponding one of theplurality of fibers in the second fiber bundle at the second end of thesecond fiber bundle, and at the second end of the second fiber bundle,forming a pattern of electromagnetic radiation corresponding to thescene, and wherein the receiving includes obtaining an image of thesecond end of the second bundle, in order to determine a direction to anobject in the scene.

In some embodiments, the receiving of the electromagnetic radiation fromthe scene includes directing electromagnetic radiation from each of aplurality of different directions into a corresponding one of theplurality locations on an imaging sensor, wherein the sensor includes acamera that obtains an image of the scene, in order to determine adirection to an object in the scene.

In other embodiments, the present invention provides an apparatus thatincludes a first fiber bundle having a plurality of light-transmittingfibers including a first fiber, a second fiber, and a third fiber, thefirst fiber bundle having a first end and a second end, means forgenerating direction-control information, means for directing laserenergy, based on the direction-control information, into the first fiberat the first end of the first fiber bundle during a first time period,means for forming an output beam of the laser energy from the second endof the first fiber bundle, and means for steering the output beam of thelaser energy from the first fiber in a first selected direction of aplurality of directions during the first time period.

Some embodiments of this apparatus further include means for modulatingan intensity of the laser energy according to a predetermined pattern.

Some embodiments of this apparatus further include means for receivingelectromagnetic radiation from a scene, and means for generating thedirection-control information based on the received electromagneticradiation.

Some embodiments of this apparatus further include means for generatingsense information useful for determining a first direction toward alocation of a first moving object during the first time period, whereinthe first selected direction of the output beam of the laser energy isthe first direction toward the location of the first moving objectduring the first time period, wherein the sense information laterincludes information useful for determining a second direction toward alocation of the first moving object during a second time period, basedon the direction-control information, directing the laser energy intothe second fiber at the first end of the first fiber bundle during thesecond time period and forming an output beam of the laser energy fromthe second fiber in a second selected direction of the plurality ofdirections during the second time period, and wherein the secondselected direction of the output beam of the laser energy is the seconddirection toward the location of the first moving object during thesecond time period, in order to track the first object.

Some embodiments of this apparatus further include means for generatingsense information useful for determining a third direction toward alocation of a second moving object during a third time period, means fordirecting the laser energy, based on the direction-control information,into the third fiber at the first end of the first fiber bundle duringthe third time period, and means for forming an output beam of the laserenergy from the third fiber in a third selected direction of theplurality of directions during the third time period, and wherein thethird selected direction of the output beam of the laser energy is thethird direction toward the location of the second moving object duringthe third time period, in order to also track the second object.

Some embodiments of this apparatus further include a second fiber bundlehaving a plurality of light-transmitting fibers including a first fiber,a second fiber, and a third fiber, the second fiber bundle having afirst end and a second end, means for receiving the electromagneticradiation from the scene and directing the electromagnetic radiationfrom each of a plurality of different directions into a correspondingone of the plurality of fibers in the second fiber bundle at the secondend of the second fiber bundle, and means for forming, at the second endof the second fiber bundle, a pattern of electromagnetic radiationcorresponding to the scene, and wherein the means for receiving includesmeans for obtaining an image of the second end of the second bundle, inorder to determine a direction to an object in the scene.

In some embodiments, the means for receiving the electromagneticradiation from the scene includes means for directing electromagneticradiation from each of a plurality of different directions into acorresponding one of the plurality locations on an imaging sensor,wherein the sensor includes a camera that obtains an image of the scene,in order to determine a direction to an object in the scene.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Although numerous characteristics andadvantages of various embodiments as described herein have been setforth in the foregoing description, together with details of thestructure and function of various embodiments, many other embodimentsand changes to details will be apparent to those of skill in the artupon reviewing the above description. The scope of the invention shouldbe, therefore, determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein,” respectively. Moreover, the terms “first,” “second,” and“third,” etc., are used merely as labels, and are not intended to imposenumerical requirements on their objects.

1. An apparatus comprising: a first fiber bundle having a plurality oflight-transmitting fibers including a first fiber, a second fiber, and athird fiber, the first fiber bundle having a first end and a second end;a first transform optics unit pointed generally in a first direction toreceive electromagnetic radiation from a scene and operatively coupledto direct electromagnetic radiation from each of a plurality ofdifferent directions into a corresponding one of the plurality of fibersin the first fiber bundle at the first end of the first fiber bundle andwherein the second end of the first fiber bundle is configured to form afirst pattern of electromagnetic radiation corresponding to the scene; asensor unit operatively coupled to receive an image of the first patternof electromagnetic radiation from the second end of the first fiberbundle, and wherein the sensor unit generates a first set of senseinformation based on the received electromagnetic radiation; and animage processor operatively coupled to the sensor unit and configured toreceive and to process the first set of sense information, wherein theimage processor generates direction-control information based on theanalysis of the first set of sense information that is received during afirst time period.
 2. The apparatus of claim 1, wherein the first set ofsense information includes information useful for determining a firstdirection toward a location of a first moving object during the firsttime period, wherein a second set of sense information includesinformation useful for determining a second direction toward a locationof the first moving object during a second time period, and wherein theimage processor generates direction-control information based on thesecond set of sense information that is received during the second timeperiod.
 3. The apparatus of claim 2, wherein a third set of senseinformation includes information useful for determining a thirddirection toward a location of a second moving object during a thirdtime period, and wherein the image processor generates direction-controlinformation based on the third set of sense information that is receivedduring the third time period.
 4. The apparatus of claim 1, wherein thesensor unit includes a camera.
 5. The apparatus of claim 1, wherein thesensor unit includes a missile-warning sensor (MWS) on an aircraft, andthe apparatus is part of a countermeasures system on the aircraftintended to protect the aircraft from heat-seeking missiles.
 6. Theapparatus of claim 5, wherein the first set of sense informationgenerated by the MWS includes information useful for the image processorto generate direction-control information in a first direction from theaircraft toward a first location of a first missile during the firsttime period.
 7. The apparatus of claim 6, wherein the MWS generates asecond set of sense information that includes information useful for theimage processor to generate direction-control information in a seconddirection from the aircraft toward a second location of the firstmissile during a second time period.
 8. The apparatus of claim 5,wherein the first set of sense information generated by the MWS includesinformation useful for the image processor to generate direction-controlinformation in a first direction from the aircraft toward a location ofa first missile during the first time period, and wherein a second setof sense information generated by the MWS includes information usefulfor the image processor to generate direction-control information in asecond direction from the aircraft toward a location of a second missileduring a second time period.
 9. The apparatus of claim 1, furthercomprising: a second fiber bundle having a plurality oflight-transmitting fibers including a first fiber, a second fiber, and athird fiber, the second fiber bundle having a first end and a secondend; and a second transform optics unit pointed generally in a seconddirection to receive electromagnetic radiation from a second scene andoperatively coupled to direct electromagnetic radiation from each of aplurality of different directions from the second scene into acorresponding one of the plurality of fibers in the second fiber bundleat the first end of the second fiber bundle and wherein the second endof the second fiber bundle is configured to form a second pattern ofelectromagnetic radiation corresponding to the second scene, wherein thesensor unit is operatively coupled to receive an image of the secondpattern of electromagnetic radiation from the second end of the secondfiber bundle and based on the received electromagnetic radiation, togenerate a second set of sense information, and wherein the imageprocessor is operatively coupled to configured to receive and to processthe second set of sense information, and wherein the image processorgenerates direction-control information based on the analysis of boththe first set and the second set of sense information received duringthe first time period.
 10. The apparatus of claim 1, wherein the firsttransform optics unit includes a lens unit having a focal length, andwherein the first end of the first fiber bundle is located at one timesthe focal length from the lens unit.
 11. The apparatus of claim 1,wherein the sensor unit includes a camera and an imaging unit.
 12. Amethod comprising: providing a first fiber bundle having a plurality oflight-transmitting fibers including a first fiber, a second fiber, and athird fiber, the first fiber bundle having a first end and a second end;receiving electromagnetic radiation from each one of a plurality ofdirections of a first scene and directing the electromagnetic radiationfrom each of the plurality of different directions from the first sceneinto a corresponding one of the plurality of fibers in the first fiberbundle at the first end of the first fiber bundle and wherein the secondend of the first fiber bundle is configured to form a first pattern ofelectromagnetic radiation corresponding to the first scene; sensing animage of the first pattern of electromagnetic radiation from the secondend of the first fiber bundle and outputting a first set of senseinformation based on the image of the first pattern of electromagneticradiation sensed during a first time period; receiving and processingthe first set of sense information; and generating direction-controlinformation based on the processing of the first set of senseinformation that was sensed during the first time period.
 13. The methodof claim 12, further comprising: using the first set of senseinformation for determining a first direction toward a location of afirst moving object during the first time period; outputting a secondset of sense information based on the received electromagnetic radiationduring a second time period; using a second set of sense information fordetermining a second direction toward a location of the first movingobject during a second time period; and wherein the generating of thedirection-control information is based on the processing of the firstset of sense information during the first time period and the second setof sense information during the second time period, in order to trackthe first object.
 14. The method of claim 13, further comprising:outputting a third set of sense information useful for determining athird direction toward a location of a second moving object during athird time period; receiving and processing the third set of senseinformation; and generating direction-control information based on theprocessing of the third set of sense information, in order to also trackthe second object.
 15. The method of claim 12, wherein the sensingincludes sensing using a camera.
 16. The method of claim 12, wherein thesensing includes sensing the image of the first pattern ofelectromagnetic radiation from the second end of the first fiber bundleusing a missile-warning sensor (MWS) on an aircraft, wherein theoutputting includes outputting the first set of sense information usingthe MWS, and wherein the MWS is used in protecting the aircraft fromheat-seeking missiles.
 17. The method of claim 16, wherein the first setof sense information outputted by the MWS includes information usefulfor the generating of the direction-control information in a firstdirection from the aircraft toward a first location of a first missileduring the first time period.
 18. The method of claim 17, furthercomprising: outputting a second set of sense information by the MWSduring a second time period; and generating direction-controlinformation in a second direction from the aircraft toward a secondlocation of the first missile during the second time period.
 19. Themethod of claim 16, wherein the first set of sense information outputtedby the MWS includes information useful for the generating of thedirection-control information in a first direction from the aircrafttoward a location of a first missile during the first time period, andfurther comprising outputting from the MWS a second set of senseinformation that includes information useful for generatingdirection-control information in a second direction from the aircrafttoward a location of a second missile during a second time period. 20.The method of claim 12, further comprising: providing a second fiberbundle having a plurality of light-transmitting fibers including a firstfiber, a second fiber, and a third fiber, the second fiber bundle havinga first end and a second end; and receiving electromagnetic radiationfrom each one of a plurality of directions of a second scene anddirecting electromagnetic radiation from each of a plurality ofdifferent directions from the second scene into a corresponding one ofthe plurality of fibers in the second fiber bundle at the first end ofthe second fiber bundle and wherein the second end of the second fiberbundle is configured to form a second pattern of electromagneticradiation corresponding to the second scene, sensing an image of thesecond pattern of electromagnetic radiation from the second end of thesecond fiber bundle and outputting a second set of sense informationbased on the image of the second pattern of electromagnetic radiationsensed during the first time period; receiving and processing the secondset of sense information; and generating direction-control informationbased on the processing of the second set of sense information that wassensed during the first time period.
 21. The method of claim 12, whereinreceiving of the electromagnetic radiation includes using a lens unitand positioning the first end of the first fiber bundle at one focallength from the lens unit.
 22. The method of claim 12, wherein thesensing and the outputting include using a camera and an imaging unit.23. An apparatus comprising: a first fiber bundle having a plurality oflight-transmitting fibers including a first fiber, a second fiber, and athird fiber, the first fiber bundle having a first end and a second end;a first transform optics unit pointed generally in a first direction toreceive electromagnetic radiation from a first scene and operativelycoupled to direct electromagnetic radiation from each of a plurality ofdifferent directions from the first scene into a corresponding one ofthe plurality of fibers in the first fiber bundle at the first end ofthe first fiber bundle and wherein the second end of the first fiberbundle is configured to form a first pattern of electromagneticradiation corresponding to the first scene; means for sensing an imageof the first pattern of electromagnetic radiation from the second end ofthe first fiber bundle and for outputting a first set of senseinformation based on the sensed image of the first pattern ofelectromagnetic radiation sensed during a first time period; means forreceiving and processing operatively coupled to the means for sensingand for outputting and configured to receive and to process theoutputted first set of sense information; means for generatingdirection-control information based on the processed first set of senseinformation that was sensed during the first time period.
 24. Theapparatus of claim 23, wherein the means for outputting includes meansfor outputting a second set of sense information based on the receivedelectromagnetic radiation during a second time period; the apparatusfurther comprising means for using the first set of sense informationfor determining a first direction toward a location of a first movingobject during the first time period; means for using the second set ofsense information for determining a second direction toward a locationof the first moving object during the second time period, wherein themeans for receiving and processing is configured to receive and toprocess the outputted second set of sense information during the secondtime period, and wherein the means for generating includes means forgenerating direction-control information based on the processing offirst set of sense information during the first time period and thesecond set of sense information during the second time period, in orderto track the first object.
 25. The apparatus of claim 24, wherein themeans for outputting includes means for outputting a third set of senseinformation useful for determining a third direction toward a locationof a second moving object during a third time period, wherein the meansfor receiving and processing is configured to receive and to process theoutputted third set of sense information during the third time period,and wherein the means for generating includes means for generatingdirection-control information based on the processing of the third setof sense information during the third time period, in order to alsotrack the second object.
 26. The apparatus of claim 23, wherein themeans for sensing includes a camera.
 27. The apparatus of claim 23,wherein the means for sensing and the means for outputting are part of amissile-warning sensor (MWS) on an aircraft, and the apparatus is partof a countermeasures system on the aircraft and are operable to protectthe aircraft from heat-seeking missiles.
 28. The apparatus of claim 27,wherein the first set of sense information outputted by the means foroutputting part of the MWS includes information useful for the means forgenerating to generate direction-control information in a firstdirection from the aircraft toward a first location of a first missileduring the first time period.
 29. The apparatus of claim 28, wherein theMWS is configured to output a second set of sense information that isuseful for the means for generating to generated direction-controlinformation in a second direction from the aircraft toward a secondlocation of the first missile during a second time period.
 30. Theapparatus of claim 28, wherein the first set of sense informationoutputted by the MWS includes information useful for the means forgenerating to generate direction-control information in a firstdirection from the aircraft toward a location of a first missile duringthe first time period, and wherein a second set of sense informationoutputted by the MWS includes information useful for the means forgenerating to generate direction-control information in a seconddirection from the aircraft toward a location of a second missile duringa second time period.
 31. The apparatus of claim 23, further comprising:a second fiber bundle having a plurality of light-transmitting fibersincluding a first fiber, a second fiber, and a third fiber, the secondfiber bundle having a first end and a second end; a second transformoptics unit pointed generally in a second direction to receiveelectromagnetic radiation from a second scene and operatively coupled todirect electromagnetic radiation from each of a plurality of differentdirections from the second scene into a corresponding one of theplurality of fibers in the second fiber bundle at the first end of thesecond fiber bundle and wherein the second end of the first fiber bundleis configured to form a second pattern of electromagnetic radiationcorresponding to the second scene; wherein the means for sensingincludes means for sensing an image of the second pattern ofelectromagnetic radiation from the second end of the second fiberbundle, and wherein the means for outputting includes means foroutputting a second set of sense information based on a received imageof the second pattern of electromagnetic radiation sensed during thefirst time period, and wherein the means for generating includes meansfor generating direction-control information based on the analysis ofboth the first set of sense information and second set of senseinformation that were received during the first time period.
 32. Theapparatus of claim 23, wherein the first transform optics unit includesa lens unit, and wherein the first end of the first fiber bundle islocated one focal length from the lens unit.
 33. The apparatus of claim23, wherein the means for sensing includes a camera and an imaging unit.